The present invention relates generally to a high frequency antenna and more particularly to a planar TV receiving antenna having broad band and being able to be used to receive the TV signal from the lowest VHF channel to the highest UHF channel.
Recently, telescopic and Yagi-Uda antennas are used in TV sets, radio transmitter-receivers or other radio communication apparatus. When they are used for the reception of TV signals, due to the fact that the receiving channel of the antenna depends upon the dimension of the antenna, therefore after the dimension of the antenna is fixed, they are not suitable for operating on a broad band, even if the dimension of the antenna is adjustable, and such adjustment is usually very troublesome. In fact they are not able to obtain satisfactory results in the reception of TV signals for all channels, i.e. VHF channels and UHF channels. In U.S. Pat. No. 3,815,141, a planar high frequency antenna was disclosed, but this antenna can only be used in the ultra-high frequency band (UHF). This antenna comprises a sheet composed of two superimposed laminae of electrically non-conductive synthetic plastic foil material and a pair of triangular antenna elements of metallic foil sandwiched between them. A pair of triangular antenna elements are connected to the receiving apparatus directly by feed lines without any compensation, so the range of the operation frequency can't be broadened to VHF. Because an impedance transformer is not used and integrated with the antenna elements, it is impossible to output a receiving signal from the antenna by a coaxial cable, so the anti-interference performance is inferior and the practical value for usage is limited.